Transducer and stylus therefor



J. R. FREDERICK 2,742,295

TRANSDUCER AND STYLUS THEREFOR 2 Sheets-Sheet J.

April 17, 1956 Filed March 31, 1951 ll l2 l0 \x\ O 0 1 1 M 5 O 0 25 4 k. gwuvwto'a JEAN ROBERT FREDERICK April 7, 1956 J. R. FREDERICK 2,742,295

TRANSDUCER AND STYLUSTHEREFOR 2 Sheets-Sheet 2 Filed March 31, 1951 INVENTOR JEAN ROBERT FREDERICK wil s and thestylus iise f CQR 1 t TRANSDUCER AND STYLUS THEREFOR .Ican Robert Frederick, Conneaut, Ohio, assignor to The Asta tic Corporation, Conneaut, Ohio Application Ma c 1, 195 .,S TNo- 2 8,68

' 4 Claims. (Cl. 274--;37)

ahyto ls bu hen a semb d il have an xtr tne y id and secure soh t en w th, the .nteehanica dr ving el m nts .92 he transduce to her by give sup rior i ra ion transihsr sult and wh reby the stylusthay be sed shs eht lIY in it en ire y in. a rece s or g o ve fo me in a smo h bo tom allv of he t an duc r car ridge tor-the protection of both the stylus and any underlying record tablet as wi l becom ppareht belo A fu ther ehieetof my have ion s the pro is on o an improv d stylu itornse in the. ih nr ed assemb y outn d abo e whieh will ha e sutfi ent teompl ahe in an la e al d re t qu to rep odu in b nai i ht he t ansducer, the fr quen es and amp itud s of the record undulation with utmo fide i "United States Patent 0 is e nth h p act c in he de igna d. const uctio 1 Qt meehanical-e e trieal transdu e s for pho o ap production o a semb e the t n d ce itself tese i a dr fred or chuck in a. u tary cartr dge h ch may replaceab v ass mbl d in. th s ingin to a Of th rese player. "Such drive rod or shtick is u ual y m u ed to imit d ro at on l mo e ent whereby he undul ons oi he re ord roo e may he ta hihlly smi ted to the t ansduce which in many devices is a piezoelectri el me ttlas ill he under to d- 1 pre era ly u e such se. a a sembly u in accordance w th the principles of vehtioh the dr e red r e u hif posi ion d he g a l to the bottom and stylus hol er o my inven on. Also he ca t idge asemblymay he so s e-- strueted tha the driv rod t lf depend ng r la s dei eu lins memhe 1s e. the lo e en ief the o attachm nt o the sts of a g ne ally ho i ontallvd p sed mem er hea in a ts o te t ee lend a 'oovesofthereeo ti s a numbe of a vantages, n-addttieh tnthsse me t oned above, wh ehwi l become apparent upon consideration of the following detailed speci icat on and "the aeso hnah ihs drawing 18 p sitioned ettiea v in wherein thereis disclosed apreferred embodiment of the invention: i in the drawing: 1 a

jFigur-e-lis a ragmentarys-ideelevation, partly "broken away; of atom: arm bearing a-transducer cartridge having stylus-and-stylusholder of my. invention;

T Figure 2;is,a perspective view of th captridge and stylus assembly ofwFigure '1, the assembly being inverted'for elari vot illus lifis trs Bisa Perspective view of hehnpmv g gyms my invention; 7 v

. 2,742,295 Patented Apr- .17, 956

Figure 10 is a modified form of stylus constructed in" accordance with the principles of my invention;

Figure 11 is a fragmentary view of yet another form of stylus constructed in accordance with my invention;

Figure 12 shows the stylus of Figure 11 inserted in a stylus holder; and

Figures 13 and 14 are front and rear perspective views, respectively, of the stylusholder of Figure 12.

In Figure 1 of the drawing, the reference numeral 10 designates the free end portion of a conventional tone arm which is open along its bottom edge for insertion of the transducer cartridge therein designated generally by the reference numeral 11. The cartridge 11 is releasab'ly retained in the arm 10 by friction and by spring clips .12 which are carried by the arm and which also serve as electrical connectors-contacting the electrical contacts 13 projecting rearwardly out of the casing of the cartridge 11. Housed within the casing of the cartridge 11 is a mechanical-electrical transducer, not shown, which is provided with a driving member of either of the types mentioned above-having a depending actuating rod 14 posi cartridge 11v is formed with a slightly convexed bottom surface 15 which is polished smoothly so as to avoid injury to the record surface in case the transducer cartridge is brought into engagement -with such surface. Formed longitudinally in the bottom surface 15 is a fairly wide and deep groove '16 to receive the stylus and stylus holder to be described below. It should be observed that the bottom wall of the transducer cartridge extends outwardly beyond the side walls thereof to form a peripheral flange 17 which is serrated as shown to facilitate gripping of the cartridge with the fingers and insertion and removal thereof with respectto the tone arm.

Rigidly secured to the lower free end of the drive rod 14 and housed within the central portion of the groove 16 is a stylus holder 18 in the form of a longitudinally disposed'plate having its side edges bent downwardly and inwardly as at 19; The side edge portions 19 are bent inwardly along converging lines so that there is provided in effect a tapering socket for the reception of the stylus new to hei seri d- Th ylus of y nv nt on h ap heip l y po formed of a unitary piece of sheet metal and as shown in Figures 3, 5 and 6 it is provided witha tapering anchor se ie 29 for l d n fit in the sock l t s with one end of the section 20 is 21 depending tab 21 and integral with the opposite @hd of the section 20 is a longitudinally disposet shahk hi h s t i t e Pr d a Section 22 lying in a vertical plane vandan outer section 23 lying in a substantially horizontal plans. As shown, the sections 22 and 23 are generally aligned with each other but are til ed .dewhw td y'w h resp s t th ancho n ction and theouter extremity of the shanlg of the stylus is bent upwardly asat Zslto mount a forwardly and downwardly extend hs ti wardly bent side edge portions 19 of the holder 18. The

tapering configurations of the parts'causes the stylus to become tightly wedged in the holder and the inwardly bent nature of the side edge portions 19 of the holder forces the fiat anchoring portion'20 of the stylus into tight fiat engagement with the fiat center portion of the holder. This insures that the stylus will be properly oriented and aligned with respect to the drive rod 14. The stylusmay be readily removed by engaging the depending tab 21 with the thumb nail and applying rearward force to thereby disengage the stylus from the socket.

By referring to Figure i it will be observed that the only portion of the stylus and its holder which projects below the smooth bottom surface 15 of the transducer cartridge is the tab 25 and sections 23 and 24. Since these are located at the outer free end of the shank of the stylus and since this shank is quite long and flexible these parts are easily moved into the surface of the lower wall of the cartridge so that in the event the tone arm is dropped on the record or if an unusual downward force is applied to the outer free end of the tone arm the smooth surface 15 will come in contact with the record to thereby avoid injury to either the record or the stylus or the transducer. in the embodiment of the invention shown in Figures 7, 8 and 9 the that horizontal portion of the stylus holder is elongated fore and aft as at 26 and 27, respectively, to increase the longitudinal bearing of the stylus if considered necessary or desirable.

in the embodiment of the invention shown in Figure 10 the main body portion 20a of the stylus is made separately I from the shank portion 22a and 23a of the stylus, these two parts being preferably joined together by a pair of spot welds as shown at 2612. This construction enables the shank portion of the styl'u's to be fabricatedof aging of metal of uniform cross-sectional shape and areaand, further, enables this portion of the stylus to be fabricated of spring stock which may not be particularly suitable or which is too expensive for the part Zita. i

In the embodiment of the invention shown in Figures 11 through 14 the principal body portion Ziic. of the stylus is arcuately deformed in a vertical direction as shown and the flanged side edge portions of the stylus holder 18a are rolled inwardly to provide a more secure bearing for the bottom surface of the body portion 200 of the stylus when the latter is slid longitudinally into position in the holder as shown in Figure 12. In practice, the stylus 2t)c22c as well as the holder 13a are preferably made of stainless steel having high strength, corrosion-resistance, and spring qualities. Upon the parts being assembled the inwardly rolled flanges 1% tightly engage the center portion of the convex bottom surface of the stylus part 290 as indicated at A in Figure 12 to thereby force the ends of the portion 29c into tight engagement withthe fiat base of the holder 3.8a as shown at B and C. This provides a simple yet extremely rigid mounting for the stylus in the holder and insures against any looseness between these parts which might effect the fidelity of the sound reproduction. Never theicss, the stylus is easily removed and replaced by engag ing the integral tab 21c with a finger nail or any common tool and moving the same in the diverging direction of the holder l8a.

It should be observed particularly that in any of the embodiments herein shown the stylus is readily replaceable in the holder with the holder in position in the groove of the cartridge casing. This is so because the direction of longitudinal sliding movement of the stylus when insorting and removing the same is coincident with the longitudinal axis of the groove in the bottom wall of the cartridge housing. It should therefore be apparent that I have provided an improved transducer-and stylus combination and an improved stylus and holder which accomplishes the objects initially set out. The parts are simple in design and economical to produce but yet are very easily assembled with or without the aid of tools and when assembled provide a steadfast and efiicient driving interconnection between the stylus tip and the transducer housed in the cartridge. Further, while the stylus is horizontally elongated to allow ready vertical ilexure whereby valuable record tablets may be protected the stylus is located almost entirely in a protective groove formed in the bottom wall of the cartridge casing and may readily be removed and replaced in said groove.

Having thus described the principles and advantages of my invention and certain representative structures for utilizing the invention what I claim is novel and what I desire to secure by Letters Patent is:

I. In a phonograph pick-up having a casing formed with a bottom wall and enclosing a transducer the improvement which comprises a longitudinally extending groove in said bottom wall, a driver for said transducer mounted in said casing for pivotal movement about a vertical axis, a stylus holder rigidly secured to the lower end of said driver and extending longitudinally-in said groove, said stylus holder comprising an elongated plate having downwardly and inwardly directed side edge flanges converging toward each other in the longitudinal direction and being narrower at the forward end of said plate, anda stylus having a wedge-shaped body, portion adapted to be slidably received in a forward longitudinal direction in said holder and having a flexible longitudinally extending shank portion mounting a record-engaging tip, said body portion as well as said shank portion being substantially wholly received in said groove along with said holder.

2. Apparatus according to claim 1 further characterized in that said shank portion of said stylus projects outwardly from, one longitudinal end of said body portion, and said body portion having an integral downwardly extending tab at its other end portion. i f j 1 3., Apparatus according to claim 1- further characterized in that said body portion is arcuately deformed in'a vertical' direction so as to present the convex surface thereof in a downward direction, said flanges engaging and exerting an upward pressure on said convex surface intermediate the longitudinal ends thereof whereby said body portion is caused to forcibly contact said plate at two spaced points adjacent the ends of said body, portion.

4. A stylus assembly for phonograph reproducing apparatus comprising an elongated and generally horizontally extending flat body member, said body member being wedge-shaped in horizontal outline and being narrower at its forward end, an elongated yieldable shank projecting from said forward end of said body member and mounting a downwardly directed record engaging tip on its outer free end, an integral tab extending downwardly from the other end of said body member; said stylus assembly adapted to be slidably received in an assembly comprising a casing formed with a longitudinally. extending groove in'the bottom wall and supporting a transducer, a vertically disposed driver for said transducer, and a stylus holder rigidly secured to said driver and extending longitudinally in said groove and having an elongated plate with downwardlyand inwardly directed side edge flanges converging toward each other and being narrower at the forward end of said plate and said stylus holder being complementary to said wedge-shaped body member and adapted to frictionally receive said body portion upon forward horizontal application of said body portion into said holder in a forward longitudinal direction.

References Cited in the file of this patent 

